Coupled aerostructural shape and topology optimization of horizontal-axis wind turbine rotor blades

• Published in: Energy conversion and management 2020-05, Vol.212 (C), p.112621, Article 112621
• Main Authors: Wang, Zhijun, Suiker, Akke S.J., Hofmeyer, Hèrm, van Hooff, Twan, Blocken, Bert
• Format: Article
• Language: English
• Subjects: Aerodynamics; Aerostructural design; Algorithms; Computer applications; Computer simulation; Design; Finite element method; Horizontal Axis Wind Turbines; Isotropic material; Iterative methods; Multi-objective optimization; Multiple objective analysis; Optimization; Rotor blades; Rotor blades (turbomachinery); Shape optimization; Topology; Topology optimization; Turbine blades; Turbines; Wind power; Wind turbine blade; Wind turbines
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2020.112621

•Novel optimization method for aerostructual design of HAWT rotor blades.•Shape and topology optimizations are coupled in a single framework.•Beam FEM and BEM models are used to efficiently simulate blade aerostructural responses.•A multi-objective optimization model is built based on the weighted sum method.•The outer shape and interior layout of blades can be optimized simultaneously. Traditionally, Aerodynamic Shape Optimization (ASO) and Structural Topology Optimization (STO) are considered as two separate, consecutive stages in the aerostructural design process of wind turbine rotor blades. Since such a modeling strategy does not adequately account for the coupling effects between the blade aerodynamics and its structural performance, in this paper a Coupled Multi-objective Shape and Topology Optimization (CMSTO) approach is presented, which simultaneously optimizes the outer shape and the interior structural layout of the turbine blade from aerodynamic and structural requirements. The framework uses the weighted sum method, whereby the sum of the aerodynamic and structural objectives multiplied by specific weighting factors is minimized employing an incremental-iterative update procedure. The coupled optimization process is performed by sequentially carrying out shape and topology optimization steps for beam-type structures, in accordance with a staggered scheme. For the aerodynamic and structural optimizations the rotor power coefficient and the blade structural compliance are considered as the objectives, respectively. The aerodynamic response of the blade is evaluated by the Blade Element Momentum (BEM) method, which, together with a reduced beam-type Finite Element Method (FEM) model that simulates the structural response, facilitates the application of a gradient-based algorithm with analytical sensitivities. Accordingly, the computational efficiency of the CMSTO framework is warranted. The shape design variables are characterized by the locations of Non-Uniform Rational B-Splines (NURBS) control points that parameterize the blade outer shape. The topology design variables are represented by the relative densities assigned to the finite elements modeling the blade cross-sections, in correspondence with the Simplified Isotropic Material with Penalization (SIMP) method. The CMSTO framework is used to optimize the NREL 5 MW reference rotor blade, whereby the results are compared to those obtained from a separate ASO-STO approach and a pure STO appr